X-Git-Url: https://jxself.org/git/?p=ssic.git;a=blobdiff_plain;f=README;h=679265e6720cfe5243c3797ae700fc503b342d02;hp=c7a39557853c362801192f79aca9566c6ed13d9e;hb=HEAD;hpb=f9ebc012e5ba9fe05cc17804346da7920d786f61

diff --git a/README b/README
index c7a3955..679265e 100644
--- a/README
+++ b/README
@@ -15,7 +15,7 @@ superset of those supported by the old NCSA HTTPd and a subset of those
 supported by Apache HTTPd's `mod_include`:
 
     http://web.archive.org/web/19971210170837/http://hoohoo.ncsa.uiuc.edu/docs/tutorials/includes.html
-    http://httpd.apache.org/docs/current/mod/mod_include.html
+    http://httpd.apache.org/docs/2.2/mod/mod_include.html
 
 ssic uses the `CGI::SSI` Perl module for directive processing.
 
@@ -61,6 +61,8 @@ Include Variables
 
 The following variables are set:
 
+  * `__SSIC__` indicates that the Server Side Includes Compiler is being
+    used to process the document's SSI directives.
   * `DATE_GMT` is the current date in UTC.
   * `DATE_LOCAL` is the current date in the local timezone.
   * `DOCUMENT_NAME` is the current filename.
@@ -69,6 +71,51 @@ The following variables are set:
   * `DOCUMENT_URI` is the current filename.
   * `LAST_MODIFIED` is the modification date of the current document.
 
+Flow Control Commands
+---------------------
+
+The flow control commands are:
+
+    <!--#if expr="test_expression" -->
+    <!--#elif expr="test_expression" -->
+    <!--#else -->
+    <!--#endif -->
+
+If `test_expression` evaluates to false, processing of basic commands is
+suspended until the next `elif`, `else`, or `endif` is encountered.  If
+`test_expression` evaluates to true, processing of basic commands is
+suspended between any following `elif` or `else` commands and the next
+`endif` command.
+
+`test_expression` is a Perl expression, which is passed to Perl's
+`eval()` function.  Variables may be expanded but should be quoted.
+
+The following example will output "foo is bar" if the variable `foo` is
+set to the value "bar":
+
+    <!--#if expr="'$foo' eq 'bar'" -->
+            foo is bar
+    <!--#endif -->
+
+The following example checks the SSI interpreter and uses the correct
+expression syntax for either ssic or `mod_include` from Apache HTTPd 2.2
+or earlier:
+
+    <!--#if expr="'$__SSIC__' eq '__SSIC__'" -->
+        <!-- Apache HTTPd 2.2 mod_include -->
+        <!--#if expr="$foo = 'bar'" -->
+            foo is bar
+        <!--#endif -->
+    <!--#else -->
+        <!-- Server Side Includes Compiler -->
+        <!--#if expr="'$foo' eq 'bar'" -->
+            foo is bar
+        <!--#endif -->
+    <!--#endif -->
+
+This is the recommended way to check the value of the variable
+`__SSIC__`.
+
 
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 =====================